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(No Model.) 3 Sheets-Sheet 1. H. D. DUNBAR & W. L. AUSTIN.

STEAM BRAKE VALVE. No. 419,508.

Patented Jan. 14, 1890.

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STEAM BRAKE VALVE. N 419 50 Patented Jan. 14, 1890.

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H. D. DUNE-A1281; W. L. AUSTIN. STEAM BRAKE VALVE.

N0. 419,508. Patented Jan. 14, 1890.

UNITED STATES PATENT OFFICE. 5

HENRY D. DUN BAR, OF HARTLAND, VERMONT, AND IVILLIAM L. AUSTIN, OFPHILADELPHIA, PENNSYLVANIA.

STEAM-BRAKE VALVE.

SPECIFICATION forming part of Letters Patent No. 419,508, dated January14, 1890.

Application filed March 5. 1888- Sen'al No. 266,148. (No model.)

To all whom it may concern.-

Be it known that we, HENRY D. DUNBAR, of Hartland, WVindsor county,Vermont, and \VILLIAM L. AUSTIN, of Philadelphia; Pennsylvania,botlrcitizens of the United States, have invented certain Improvementsin Steam-Brake Valves, of which the following is a specification.

The object of our invention is to so construct valve mechanism forsteam-brakes, &c., that the pressure of steam admitted to thebrake-cylinders can be regulated and the brakes applied to the wheels ofthe locomotive or cars with different degrees of pressure, and so that acirculation of steam through the pipes and passages can be constantlymaintained, if desired, to prevent freezing of the water of condensationin said pipes or passages in cold weather.

In the accompanying drawings, Figure 1 is a diagram showing steam-brakecylinders having connections and valve in accordance with our invention.Fig. 2 is a side view of part of the same on a larger scale. Fig. 3 is avertical section, partly in elevation, of our improved valve. Fig.4 is asectional plan on the line 1 2, Fig. 3, with the valve removed to showthe valve-seat. Fig. 5 is an inverted plan view of the valve. Fig. 6 isa section of the valve on the line 3 4, Fig.5; and Figs. 7, 8, 9, and 10are diagrams showing the valve in different positions in respect to theports of the seat.

The steam-brakes to which our invention more particularly relates areused to brake the wheels of a locomotive, and the valves regulatingthese brakes have been hitherto constructed so as either to apply fullpressure to the brakes or to out off the steam entirely; hence a light,or gradually-increasing pressure could not be'applied to the brakes,

the usual plan adopted when the locomotive is traveling downgrade beingto hold, the brakes off until it is necessary to check the speed, andthen to apply the brakes with full power until the momentum is checked,whereupon the brakes are again released, to be again applied when thespeed becomes excessive, thus causing a series of sudden shocks.

or jars, which are very injurious to the working parts of the engine.

By our invention we overcome the objection above described and provide avalve whereby any desired pressure of steam up v to the full pressure ofthe boiler can be applied to the brakes and maintained as long ascircumstances require by simply operat ing the handle of the valve.

Referring to the drawings, A is the main valve-casing, having thevalve-seat a, I being the inlet-port, situated in the center of thecasing and communicating with the supplypipe I at the side of thecasing, as shown in Fig. 2, E being the exhaust-port, communicating withthe exhaust-pipe E.

Bis the induction-port, communicating with the steam-brake cylinders O Cthrough the pipes B O, and D is the eduction-port, communicating withthe cylinders through the pipes O D. Y I

G is the valve, the under face of which rests upon the seat a of thevalve-casing, said valve having formed in it an induction-chamber t', aportion 2" of which is V-shaped, as shown in Fig. 5, for the purpose ofgradually opening or closing communication between the induction-chamberand the steam-cylinders through the induction-port B, as describedhereinafter. The valve G has also an eduction-chamber e, that portion ofwhich between the lines 00 a), Fig. 7, is open to the bottom of thevalve,'while the remaining portion from the line 00' to the line 00 hasat the bottom a partition-plate e, in which is ,the' eduction-port g anda smaller port j. An opening it in the top of the valve provides for thepassage of steam from the inductionchamber to the space above the valve,so that the steam pressure on the valve will be slightly greaterthan thepressure beneath the same, thus causing the valve to seat itself at alltimes.

A is a cap inclosing the valve G and secured to the casing A by means ofscrewbolts.

The valve-spindle H is adapted to a pocket in the valve and passesthrough a stuffing-box in the cap A, said spindle being provided with asuitable handle H, by which the valve may be turned, a stop h on the capserving by cont-act with a lug 72. on the valve G to arrest the movementof the latter when the port 13 is fully open.

The operation of the device is as follows: Referring to the diagrams,Figs. 7, 8, 9, and 10, Fig. 7 illustrates the valve in position to cutoff the steam from the brake-cylinder (J, the exhaust-pipe Ecommunicating through the medium of the pipes B, C, and D and ports B,D, g, and E with said brake-cylinders. If the handle is operated to turnthe valve to the position shown in Fig. 8, steam will enter the port 13and circulate through the pipes B, C, and D, through the cylinders, andthrough the ports D and and eduction-chamber e to the exhaust-port E,the inlet and outlet for the steam being about equal, and consequentlyno pressure being brought to bear upon the brakes; but if the handle isoperated so as to turn the valve to the position shown in Fig. 0 theavailable area of the induction-port B is increased considerably withoutany corresponding enlargement of the area of the portj, thus giving apartial pressure to the brakes, suflicient in most instances to reducethe speed of the engine on downgrades. The valve can be held in thisposition while traveling downgrade, so as to properly reduce the speedof the locomotive, as it will be seen that the full pressure of theboiler is applied, minus the reduction due to leakage to the exhaustthrough the small leakage-port When full pressure is required, the valveis turned still farther, or to the position shown in Fig. 10, whichentirely cuts elf leakage to the exhaust and fully opens theinduction-port l3; hence it will be seen that any degree of pressure canbe applied to the brakes.

Another important feature in this form of brake-valve is that the steammay be allowed to circulate through the brake-cylinders and theirconnecting-pipes in cold weather, when the steam is liable to condensequickly, so that the steam can be in constant circulation through thecylinders and pipes, thereby preventing to a great degree the rapidcondensation of the steam and preventing freezing of the water in thepipes, any condensed steam tion and eduction ports communicating withthe steam-brake cylinder or cylinders with a valve having induction andeduction chambers and having in the latter an exhaust-port and aleakage-port, said leakage-port being located as described in respect tothe induction-chamber of the valve, whereby it will be open to theeduction-port of the chest when.

the induction-chamber of the valve is slightly open, all substantiallyas specified.

2. The combination of the valve-chest having inlet and exhaust andinduction and eduction ports with the valve having induction andeduction chambers, said eduction-chamher having apartition with eductionand leakage ports, all substantially as specified.

3. The combination of the valve-chest having inlet and exhaust andinduction and eduction chambers with the valve having an induction-chainber with tapering front end and an eduction-chamber having apartition with eduction and leakage ports, all substantially asspecified.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

HENRY D. DUNBAR. \VM. L. AUSTIN. W'itnesses:

J. R. MAssEY, FRANK R. JORDAN.

